Posted by **Brittni** on Sunday, December 5, 2010 at 7:21pm.

an auditorium has 50 rows of seats. THe first row has 20 seats, the row has 21 seats, the third row has 22 seats, and so on. each row having one more seat than the previous row. How many seats are there all together?

- Math -
**MathMate**, Sunday, December 5, 2010 at 7:56pm
First row = 20 seats,

second row = 21 seats,

...

nth row = 19+n seats,

...

50th row = 19+50 = 69 seats

Write the number of seats in forward and reverse order:

19 + 69 = 88

20 + 68 = 88

...

44 + 44 = 88

...

69 + 19 = 88

---------

Sum = 50*(88/2) = 2200 seats

- Math -
**Amber**, Thursday, May 10, 2012 at 8:19pm
19+n

u#1=19+1

u#1=20

u#50=19+50

u#1=69

50(20+69)/2

## Answer this Question

## Related Questions

- Math - An auditorium has 50 rows of seats. The first row has 20 seats, the ...
- math - Determine the seating capacity of an auditorium with 10 rows of seats if ...
- Math - An auditorium has 30 rows of seats. It has 20 seats on the first row, 24 ...
- math (plz help) - In a movie theater, theater A has 30 seats in the first row. ...
- math - An auditorium has 49 rows of seats. The first row contains 40 seats. As ...
- math - In a movie theater, Theater A has 30 seats in the first row. Each next ...
- maths - seats are arranged in rows in a auditorium.each row has 5 more than the ...
- math- Algebra 2 - An auditorium has 49 rows of seats. The first row contains 40 ...
- arithmetic - An auditorium has 20 rows of seats.These are 20 seats in the first ...
- Math - The first row of a concert hall has 25 seats and each row after the first...